Germicidal ultraviolet light (UV-C) disinfection via robotic systems within operating rooms (ORs) can significantly reduce the transmission of bacteria and infectious diseases from patient to patient, resulting in fewer health care-associated infections. 

A problem, however, lies in the fact that the management of ORs and surgical suites is not straightforward when UV-C disinfection is employed, as treatment times can differ between rooms and treatments within the same room, according to recent research. 

While hospitals may want to estimate a consistent time in which it will likely take to perform UV-C disinfection in a given OR, the truth is that it may take longer or shorter than expected, much like the actual operations taking place, according to recent industrial engineering studies published in the American Journal of Infection Control, the Cureus Journal of Medical Science and the Journal of Clinical Anesthesia.

“UV-C equipment, when used in ORs, does not take a fixed amount of time per room. Statistical analyses need to be done by the hospital,” says Franklin Dexter, M.D., Ph.D., FASA, a professor in the department of anesthesia at the University of Iowa, Iowa City, and lead author of the three aforementioned studies. 

In Dexter, et al.’s published studies, UV-C disinfection times for 133,831 studied treatments had a mean time of approximately 18 minutes and a 90th percentile time of 26 minutes. 

“If there are 20 ORs, the average amount of time to treat the ORs will vary substantially among them,” he says. “In addition, there is substantial variability in the treatment times among treatments of the same room. This is just like variability in surgical procedures, except in this context the ‘procedure’ is the room.”

The main takeaway from Dexter, et al.’s research is that the time to treat a given OR should be considered room-specific. There is no single value for all ORs.

“A hospital facilities manager may be considering the purchase of ultraviolet disinfection robots for terminal cleaning among multiple ORs,” Dexter says. “The question is, how many should they purchase? How many rooms can reliably — with greater than 90% probability — be disinfected nightly? That is a statistical experiment question, and we showed how each hospital can figure this out using a nine-night or 19-night trial.”

The paper published in the American Journal of Infection Control (“Average and longest expected treatment times for ultraviolet light disinfection of rooms”) demonstrates a simple way for hospitals to calculate the 90th percentile specific to each room: Sort the treatment times in sequence by date, then select the 90th percentile of the most recent nine (if there are nine to 18 prior times), of the most recent 19 (if there are 19 to 28 prior times), etc.